In the design of semiconductor contacts, the performance properties of the contacts typically involve compromise. For example, because of work function alignment with the semiconductor, some materials may be preferred for electrical contacts, but these materials may not be desirable as the main material in contact with the semiconductor because their thermal conductivity, adhesion, reflectivity, etc., may not be as good as other materials. For example, in the context of visible-spectrum light emitting diodes (LEDs), silver (Ag) is the most desirable metal because of its high reflectivity. However, using conventional techniques, Ag is a mediocre electrical contact for both the n-doped and p-doped regions. On the other hand, metals such as platinum (Pt), palladium (Pd), and nickel (Ni) for the p-doped region of GaN and aluminum (Al) and titanium (Ti) for the n-doped region of GaN tend to make excellent electrical contacts due to work function alignment. However, these metals are optically absorbing, which leads to a loss of efficacy of the LED.
Therefore, there is a need for a contact has can optimize different and even competing properties of metals. The present invention fulfills this need among others.